Dear thread starter, I want you to know that pain is your body's way of warning you to "don't do that".
If you feel a pain as you described, find a way to avoid that pain?
I avoid my back pain by limiting my time on my feet, and by riding a "dutch style" (upright seating) bike.
I used to love my road bike. Here is why I cannot road bike anymore, and we cannot ignore reality:
http://photobucket.com/images/lumbosacral%20reid%20welch%201992/
((this is after two failed back surgeries...see the "u-turn" that the spinal cord root makes around the blown-out disc?))
double click on the image to see how "mechanical" failures in our bodies can be visualized, and are not to be ignored or denied.....
This is the most common form of human lower back injury.
It will tend to cause pain in the lower back, and often in the buttock, and sometimes, numbness or tingling or aching pain running down one leg.
It is not dangerous, but can become chronic if you ignore the cause.
You are less than forty? Think of your vertibral disks as leathery, "jelly donuts". They are pads filled with a sort of cushioning gel.
If you suffer a rupture of any of the disks, you get a displacement of nerve tissue, as seen in my exampled photo. Ouch forever.
In my case, typical, the disk fully ruptured, or "fractured". It felt exactly like the squirt of a jelly doughnut, mashed.
Anyone less than forty is much more likely to suffer this sort of permanent injury.
As we age, though, the disks tend to become more leathery, all the way through, and less liable to rupture.
So, if you are young, pay more attention to back and neck pain? Such pains are not "imaginary" or "sports pains", not like mere muscle aches, etc.